A typical vane-type camshaft phaser for changing the phase relationship between a crankshaft and a camshaft of an internal combustion engine generally comprises a plurality of outwardly-extending vanes on a rotor interspersed with a plurality of inwardly-extending lobes on a stator, forming alternating advance and retard chambers between the vanes and lobes. Engine oil is selectively supplied to one of the advance and retard chambers and vacated from the other of the advance and retard chambers by a phasing oil control valve in order to rotate the rotor within the stator and thereby change the phase relationship between the camshaft and the crankshaft. Some camshaft phasers incorporate the phasing oil control valve within a camshaft phaser attachment bolt which is used to secure the camshaft phaser to the camshaft. In order to achieve desired performance, a check valve may be included in the camshaft phaser which prevents oil from being back-fed to the oil source. U.S. Pat. No. 7,389,756 to Hoppe et al. describes one such camshaft phaser. While the arrangement of Hoppe et al. may be effective, implementation of the check valve may add axial length to the phasing oil control valve. Furthermore, complexity may be added to the assembly process due to the need for several small and hard to handle components which make up the check valve.
What is needed is camshaft phaser which minimizes or eliminates one or more the shortcomings as set forth above.